Suspension Mechanism

ABSTRACT

An improved suspension unit which is quite and compact is revealed. The suspension unit includes a hanger member having a load bearing portion and a front face with an aperture and a control arm having a front face with an aperture and a load bearing portion. The control arm is pivotally attached to and depends from the hanger such that the front face of the hanger and the front face of the control arm are opposed one another with the aperture on the front face of the hanger being aligned with the aperture on the front face of the control arm and with the load bearing portion of the hanger positioned above the load bearing portion of the control arm. A jounce spring and a rebound spring are coaxially mounted to a shaft having opposite first and second ends, the shaft being mounted through the aperture of the front face of the hanger and the aperture of the front face of the control arm, the rebound spring being positioned between the front face of the hanger and the front face of the control arm, the jounce spring being positioned to one side of both the front face of the hanger and the front face of the control arm.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from United States provisional patent application Ser. No. 61/238,900 which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to suspensions, particularly for use with off road vehicles and equipment.

BACKGROUND OF THE INVENTION

Leaf spring suspensions have been developed long time ago and used extensively in many off-road applications but very little changes ever been made to them. In many cases a leaf spring was used primarily as a connecting member (to carry weight of a machine) more so than as a device to isolate and dampen vibration of those machines.

A leaf spring alone has little capability to isolate vibration and cushion the ride especially if loads are heavy and terrains are rough. This is mainly due to the fact that a leaf spring member is often subject to forces and bending moments that are imposed in different directions during operation of the vehicle but the design of a simple one-element member simply does not allow flexibility required for proper functioning of a suspension to overcome these simultaneous loads and at the same time to respond and react to them differently and independently. That is why a typical leaf spring used in an off-road application is and has to be very rigid. Consequently the ride quality of the vehicle that uses such springs is more often rough, especially in the empty condition. There is no energy absorbing medium to dampen shocks and reduce natural frequency of vibration of the sprung mass The spring rate of steel leaf springs is linear and therefore the vibration frequency of the sprung mass significantly changes from empty to loaded conditions.

Springs are a limited life component. They deform (bend or twist) permanently and eventually fail due to fatigue caused by overloading or repeated loading and other unpredictable conditions that may occur. A leaf spring is a homogeneous single-element entity. Once it is cracked, bent, twisted, or broken, the entire leaf needs to be replaced. When that happens it is also very likely that other springs which work with it need to be replaced as well simply because once one spring bends, fails, or is out of service, the others need to carry the additional load and will most likely be impacted by the overload caused by the failure of the first spring. It is also due to the fact that there is no adjustments that can be made to the others to bring them to the same height/orientation of the new spring. The downtime costs plus the cost to service and replace springs could be very expensive.

SUMMARY OF THE INVENTION

The present invention is an improved suspension unit. The suspension unit includes a hanger member having a load bearing portion and a front face with an aperture and a control arm having a front face with an aperture and a load bearing portion. The control arm is pivotally attached to and depends from the hanger such that the front face of the hanger and the front face of the control arm are opposed one another with the aperture on the front face of the hanger being aligned with the aperture on the front face of the control arm and with the load bearing portion of the hanger positioned above the load bearing portion of the control arm. A jounce spring and a rebound spring are coaxially mounted to a shaft having opposite first and second ends, the shaft being mounted through the aperture of the front face of the hanger and the aperture of the front face of the control arm, the rebound spring being positioned between the front face of the hanger and the front face of the control arm, the jounce spring being positioned to one side of both the front face of the hanger and the front face of the control arm.

those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the preferred typical embodiment of the principles of the present invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a suspension unit made in accordance with the present invention.

FIG. 2 is a side view of the suspension unit shown in FIG. 1.

FIG. 3 is a cross sectional view through line A-A of FIG. 2.

FIG. 4 is an exploded view of the suspension unit shown in FIG. 1.

FIG. 5 is a perspective view of a preferred embodiment suspension unit made in accordance with the present invention.

FIG. 6 is a side view of the suspension unit shown in FIG. 5.

FIG. 7 is a cross sectional view through line A-A of FIG. 6.

FIG. 8 is an exploded view of the suspension unit shown in FIG. 5.

FIG. 9 is an exploded view of the suspension unit shown in FIG. 5 showing how the component parts are assembled together.

In the drawings, like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION OF THE INVENTION

In this document the term “axle” refers to the unsprung portion of the vehicle or unsprung mass of the machine but in reality the unsprung mass could be an assembly of its own, which may include an axle but it may also include other components supported by the suspension like a bearing, a bracket that attached the bearing to axle or a shaft with hubs and tines, etc. The vehicle may not even have an axle, in that case we will actually be referring to the spindle/hub/wheel assembly. Frame or Sub-frame is the structural portion of vehicle to which most of the components of the machine as well as the suspensions are attached. “Hanger” is the rigid interface between the frame and the rest of the suspension assembly. Hanger can be attached (welded, bolted, riveted) to frame or sub-frame. “Control Arm” is another rigid member that connects Hanger to the axle. it is pivoted to the Hanger. A Control Arm is normally configured in the assembly as a trailing arm (meaning that its pivot point is towards the front of the vehicle, and its connection to the axle is towards the rear) but in some applications it may be configured the opposite way (as a leading arm). This connection isolates the vibration of unsprung mass from the frame. The bottom attachment of control arm to axle can be either welded, U-bolted, Bolted, clamped, press fitted or any other ways as long as the connections are rigid or semi-rigid.

Referring to FIG. 1, one embodiment of the suspension unit made in accordance with the present invention is shown generally as item 10, and consists of a hanger 12 pivotally coupled to a control arm 14 with jounce spring 16 and rebound spring 28 coupled to both the hanger and the control arm to dampen the up and down movement of the control arm relative to the hanger. Jounce spring 16 is positioned to one side of control arm 14. Hanger 12 is basically the rigid interface between the frame and the rest of the suspension assembly. It can be attached to the frame or trailer sub frame of the vehicle by any means commonly available, such as by bolts, rivets or welds. Control arm 14 is a trailing arm that connects hanger 12 to the axle. For the purposes of this patent application, the term “axle” refers to the unsprung portion of the vehicle (not shown) or unsprung mass of the machine (not shown). The unsprung mass could be an assembly of its own which may include the axle but it may also include other components supported by the suspension like a bearing, a bracket that attached the bearing to axle or a shaft with hubs and tines. The connection between the control arm and the unsprung mass isolated the vibration of the unsprung mass from the frame (not shown) of the vehicle or machine. The control arm can be attached to the axle by welding, U-bolts, bolts, clamps or the like provided the connection is strong and either rigid or semi-rigid.

As best seen in FIG. 4, control Arm Bushings 48 and 46 are installed into Control Arm 14. Control Arm 14 is pivoted at the front to Hanger 12 through Control

Arm Bushings 48 and 46 and pivot bolt 42 and is attached to the axle (not shown) from the bottom. The pivot mechanism can be bolted, pinned or riveted provided that the rotation of the Control Arm at the joint can be achieved.

Jounce spring 16 is installed ahead of control arm 14 with its axis oriented in a certain angle relative to horizontal fore-aft axis and at the same time perpendicular to axis of the pivot bolt. Jounce spring 16 is sandwiched between disc 22 and face 30 of control arm 14. Rebound spring 28 is coaxially aligned with jounce spring 16 but is located between face 32 of hanger 14 and face 30 control arm 14. Front bolt 24 attaches both Jounce and Rebound springs to the control arm and to the hanger. The threaded end 50 of the front bolt engages into the retaining pin 40. Disc 22 is located ahead of Jounce spring 16 and held in place by front bolt 24. Cones 52 are provided to align springs 16 and 28 to the axis of bolt 24. They also prevent wear between the bolt and the springs that may happen otherwise.

Retaining pin 40 is inserted horizontally into slot 38 of hanger 14. The axis of the retaining pin 40 is parallel to the pivot bolt 42. Retaining pin 40 is threaded in the middle allowing end 50 of the front bolt 24 to engage into it such that the retaining pin is perpendicular to the front bolt. When retaining pin 40 is installed in the suspension unit, the retaining pin articulates such that the orientation of the threaded section of the retaining pin will be an outcome of the bolt position. Retaining pin 40 can freely rotate and roll in slot 38 in control arm 14, allowing front bolt 24 to adjust its angle relative to the frame (not shown) as the suspension articulates up and down. This feature enables bolt 24 to articulate (in a vertical fore-aft plane) and thus eliminates any unnecessary bending moments being induced in the bolt. Retaining pin 40 is also a mechanical stop and a safety device for the suspension.

Each end of pin 40 is located in a kidney shaped slot 38 that encompasses the relative motion of the pin during operation of the suspension. When retaining pin 40 reaches to the end of slot 38 it locks the arm to the hanger at the end of the stroke preventing any additional movement at the end of the stroke. This is also a safety device in case something fails. For example it brings the frame to a complete stop in case for any reason jounce spring 16 fails. If the suspension unit 10 is used on an aerator for example (not shown), this last feature will prevent the tines of an Aerator to suddenly strike the frame. Springs 16 and 28 may comprise any type of spring, such as coil springs, pneumatic springs or resilient polymer springs. Preferably Aeon rubber springs are used since they inherently absorb the kinetic energy during a complete cycle and; therefore, suspensions using them may not need an additional shock absorber. If coil springs are used (or any other spring which is not intrinsically dampening) an additional shock absorber can be used in conjunction with the rest of the suspension assembly to further enhance the ride quality.

Referring back to FIG. 2, during use, hanger 12 and control arm 14 move relative to each other in a relatively vertical up and down direction as indicated by arrow 18. This substantially vertical up and down movement is then translated into a side to side movement of springs 16 and 28 as indicated by arrow 20. The direction of movement of springs 16 and 28 is at an obtuse angle to the direction of movement of control arm 14. This permits the larger spring 16, to be positioned to one side of control arm 14 and not between the control arm and the hanger.

Referring now to FIG. 5, a preferred embodiment of the present invention is shown generally as item 100 and includes hanger 102, control arm 104 and jounce spring 106. Hanger 102 has front face 108 and load bearing portion 110. Front face 108 is at an angle from load bearing portion 110. Control arm 104 has front face 112 and load bearing portion 114. Front face 112 is at an angle from load bearing portion 114. Control arm 104 and hanger 102 are pivotally connected to one another by pivot bolt 134 and nut 144. The suspension unit 100 is essentially an inverted version of the suspension unit 10 shown in FIG. 1. It has been discovered that the arrangement of hanger and control arm shown in FIG. 5 has different (improved) ride characteristics for certain applications.

Referring now to FIGS. 6 and 7, the suspension unit is provided with jounce spring 106 and rebound spring 116. Front face 108 of hanger 102 has an aperture 118 and front face 112 of control arm 104 has an aperture 120. Hanger 102 and control arm 104 are pivotally coupled to each other and dimensioned such that apertures 118 and 120 are approximately coaxially aligned when load bearing portion 110 of hanger 102 and load bearing portion 114 of control arm 104 are parallel. Jounce spring 106 has passage 150 and rebound spring 116 has passage 152. Jounce spring 106 and rebound spring 116 are coaxially aligned and mounted to bolt (shaft) 122, with the rebound spring positioned between front faces 108 and 112 and jounce spring 106 positioned to one side of both front faces and opposite load bearing portions 110 and 114. Bolt 122 has opposite ends 128 and 130. Disk 124 is secured to end 130 by nut 132 and is used to secure spring 106. Springs 106 and 116 are arranged such that front face 108 is positioned between them. Retaining pin 126 is mounted at end 128 of bolt 122. Retaining pin 126 is parallel to bolt 134 and is perpendicular to bolt 122. Retaining pin 126 is retained in kidney shaped aperture 146 formed on hanger 102. Referring now to FIGS. 8 and 9, hanger 102 is pivotally connected to control arm 104 via pivot bolt 134. To reduce friction and wear, bushing sleeve 138 and bushings 140 enclose pivot bolt 134 in barrel portion 149 of control arm 104. Nut 144 keeps pivot bolt 134 secure. Springs 106 and 116 are coaxially mounted to bolt (shaft) 122 with bolt guides 142 positioned on either side of each spring to help guide and mount the springs to the bolt. Washer 143 is positioned at the end 130 of bolt 122 to aid in mounting disk 124. As mentioned above, retaining pin 126 is mounted towards end 128 of bolt 122 and is dimensioned to fit in aperture 146. As best seen in FIG. 9, bolt 122, aperture 120 of front face 112, spring 116, aperture 118 of front face 108, and spring 106 are all mounted along axis 160. Control Arm Bushings are installed into the Control Arm. Control Arm is pivoted at the front to Hanger through Control Arm Bushings and is attached to axle from the bottom. The pivot mechanism can either be bolted, pinned, riveted provided that the rotation of Control Arms at the joint can be achieved.

Referring now to FIG. 6, hanger 102 and control arm 104 have load bearing portions 110 and 114, respectively. The hanger is pivotally mounted to the control arm such that load bearing portions 110 and 114 can move up and down relative to each other in the direction indicated by arrow 164. Jounce spring 106 and recoil spring 116 are positioned relative to front faces 108 and 120 such that as the hanger and control arm move in the direction indicated by arrow 164 the springs are forced to move in the direction indicated by arrow 162. As a result, the jounce and recoil springs dampen the up and down movement of load bearing portions 110 and 114 even though the springs are positioned away from and to the side of the load bearing portions. As the hanger and control arms move up and down, retaining pin 126 moves within aperture 146, securing the end of bolt 122 and keeping springs 106 and 116 in alignment.

The retaining pin has several functions. When retaining pin 126 is installed in the suspension it articulates such that the orientation of the threaded section will be an outcome of the bolt position. It can freely rotate and roll in its housing holes in the hanger allowing Thru Spring Bolt 122 to adjust its angle relative to the frame freely as suspension articulates up and down. This feature enables bolt to articulate (in a vertical fore-aft plane) and thus eliminates any unnecessary bending moments being induced in the bolt. The retaining pin is also a mechanical stop and a safety device for the suspension. Each end of the retaining pin is located in a kidney shaped slot that encompasses the relative motion of the pin during operation of the suspension. When retaining pin reaches to the end of the slot it locks the arm to the hanger at the end of the stroke preventing any additional movement at the end of the stroke. This is also a safety device in case something fails. For example it brings the frame to a complete stop in case for any reason the jounce spring fails. This will prevent tines of an Aerator to suddenly strike the frame.

Springs 106 and 116 (and springs 16 and 28) can be any type of compression spring such as a coil spring or even a pneumatic spring; however, springs made of an electrometric material (such as rubber) are preferable due to their dampening and low noise qualities. Although some type of springs like Aeon rubber springs inherently absorb the kinetic energy during a complete cycle and therefore may not need an additional shock absorber others like coil springs may not. This suspension can work with different types of springs with that may have different load characteristics. Although it is not shown here, an additional shock absorber can be used in conjunction with the rest of the suspension assembly to further enhance the ride quality.

The present suspension unite improves ride characteristics. Suspension system, as a whole absorbs energy and shock loads both in jounce and rebound. Certain elastomer springs and bushings constantly absorb energy during jounce and re-bound of axle when vehicle is in motion. That gives the suspension the ability to dampen shock loads and therefore reduce the amplitude of the vibration for the vehicle body (sprung mass). It provides lower natural frequency for the sprung mass, especially in the empty condition, because unlike steel springs the elastomer springs like rubber have lower spring rates in empty conditions and higher spring rates in loaded conditions. Reducing shock loads would increases life of other components of the machine (like bearings of an aerator equipment). Each side of suspension flexes and reacts independently to conform to the shape of bumps and potholes of the ground, allowing contour-ability to accurately follow uneven land, therefore reducing tension induced in the frame and reducing vibration of the frame and other attachments of the frame.

Since spring 106 is tilted and positioned to the side of the hanger and control arm, and since the bolt is exposed and is easily accessible, the ride height of the suspension can be changed simply by loosening or tightening bolt 122 which in turn, changes the pre-load on the springs. That feature is a simple means that can be used to raise or lower the frame to achieve the optimum height necessary to accommodate different loads (to add to the machine or take from it which may be necessary for the same machine that might work in different fields). The stiffness of the suspension can also be adjusted by replacing the springs to harder or softer ones. Alternatively, the stiffness (hardness or softness) of the suspension can be adjusted by changing the preload on the spring (only for nonlinear type springs). Since spring 106 is positioned to the side of the hanger and control arms, replacing the spring or adjusting bolt 122 can be done in the field and without specialized tools. In fact, the suspension can be easily disassembled and re-assembled. Any part including the spring and bushings can be replaced in the field using ordinary tools.

The location of the Jounce and Rebound springs are chosen such that deflection on the springs (measured along their own axes) would be multiplied with a certain ratio to axle in up-down direction. In other words, the geometry of suspension allows amplifying relative motion between and frame and axle (deflection for the sprung mass) for Off-Road use WITHIOUT using larger and taller springs. This feature also helps reduce frequency of vibration and hence further improve ride characteristics. The suspension also functions quietly. The moving parts of the new suspensions do not squeak since the Elastomer springs themselves do not squeak. There is no steel on steel contact between moving parts. There is no need to lubricate the joint; although lubricated joints can be used in this design as well.

Finally, the suspension unit is very simple to install. Most of the time all it takes to install it is commercially available fasteners and regular tools to mount the suspension to the frame from top and to the axle from bottom. Suspension can be installed on steel, aluminum, or composite type frames.

A specific embodiment of the present invention has been disclosed; however, several variations of the disclosed embodiment could be envisioned as within the scope of this invention. It is to be understood that the present invention is not limited to the embodiments described above. 

Therefore, what is claimed is:
 1. A suspension unit comprising: a. a hanger member for coupling beneath the load, the hanger member having a load bearing portion and a front face; b. a control arm for coupling to the wheel, the control arm having a front face with an aperture and a load bearing portion; c. the control arm being pivotally attached to and depending from the hanger such that the front face of the hanger and the front face of the control arm are opposed one another with the aperture on the front face of the hanger being aligned with the aperture on the front face of the control arm and with the load bearing portion of the hanger positioned above the load bearing portion of the control arm; d. a jounce spring and a rebound spring coaxially mounted to a shaft having opposite first and second ends, the shaft being mounted through the aperture of the front face of the hanger and the aperture of the front face of the control arm, the rebound spring being positioned between the front face of the hanger and the front face of the control arm, the jounce spring being positioned to one side of both the front face of the hanger and the front face of the control arm.
 2. The suspension unite of claim 1 wherein the jounce spring is oriented away from the load bearing portion of the hanger and the load bearing portion of the control arm.
 3. The suspension unite of claim 2 wherein the front face of the hanger is at an angle from the load bearing portion of the hanger and wherein the front face of the control arm is at an angle from the load bearing portion of the control arm, the hanger and control arm being pivotally mounted to each other such that the load bearing portions of the control arm and hanger are roughly parallel to each other.
 4. The suspension unite of claim 1 wherein the first end of the shaft is provided with a stop to prevent the jounce spring from slipping off the shaft and wherein the jounce spring is positioned between the stop and one of the faces of the hanger and control arm such that when the load bearing portions of the control arm and the hanger move towards each other the jounce spring is compressed.
 5. The suspension unite of claim 4 wherein the second end of the shaft is provided with a retaining pin extending perpendicularly to the shaft, the retaining pin having opposite ends which are engaged in a guide groove formed on one of the hanger and control arm. 